Maxperson
Morkus from Orkus
So, in one campaign, we play a high RP game with virtually no combat and barely reference any rules for sessions on end. In another, we play a down and dirty dungeon crawl with pretty much zero RP and nothing but endless tactical combat.
I'm playing the same game?
100%. Virtually no combat still entails some combat using the same rules. The same skills you use in a dungeon crawl are also used in the high RP game. The same rules to make characters are used in both. Treasure is the same rules wise from one to the other. The same monsters exist for the DM to use or make up if he so chooses. Both games are designed around the same number of encounters per day. And so on. The same amount of exp is required for character to go up in level.
Or, put it another way. Let's see you create my Primeval Thule campaign. We're using the same rules right? So, you should be able to create my campaign with no problems.
Being the same game is not the same as identical results. This is a False Equivalence you are engaging in. There is no difference between Settlers of Catan resulting in different set-ups(hex layout and numbers) each time you play a game of it, and D&D resulting in different set-ups(campaign design and goals) each time you play a game of it. The differences are that D&D doesn't end after a few hours and one game of it can last for years, and the D&D rules describe how to play the game, rather than prescribe how to play the game.